The objective of this project is to: a) identify and find solutions to those problems in basic physics, dosimetry, and clinical applications associated with the use of charged beams in the treatment of human cancer. This will be accomplished by collaborative efforts between physicists who are actively working on projects where patients are already being treated with charged particle beams or where serious efforts are underway to develop such projects; b) to design and build a calorimeter suitable for the absolute calibration of charged particle beams (to be done in collaboration with recognized leaders in the field of calorimetry); c) to perform intercomparisons between charged particle beams at various facilities so that a common dose standard can be developed for the statement of patient doses at all facilities. Charged particle therapy is in a period of rapid development. As in any new field there are unsolved problems, many of which are common to all of the projects regardless of which particle is employed. This task group will ensure the compatibility of dosimetry practices at all facilities and will enable earlier and more efficient solutions to be found to pressing problems. An important result of this work will be the development of a charged particle beam dosimetry protocol which will serve as a standardizing document for all charged particle therapy facilities and as a guide to agencies which may oversee the quality control of charged particle beam clinical trials.